ASR-2

The City's water supply is supplemented through the use of Aquifer Storage and Recovery (ASR) technology. ASR allows the City to capture, treat and store underground excess flows of water over our dam during the rainy season, and recover that water from the ground during dry periods of the year. ASR is achieved through the use of wells drilled into the aquifer system underground. The same wells are used to inject water into the ground and recover that stored water. The City has two ASR wells that collectively are permitted to store nearly 400 million gallons of drinking water.

The City has been a leader in the application of degasification technologies to control the mobilization of arsenic in the subsurface environment associated with ASR. Arsenic mobilization can result from the geochemical reaction between oxidizing agents in potable water with naturally occurring pyrite in aquifer formations. With its first ASR well (ASR-1) the City partnered with the Florida DEP and several of the Water Management Districts in the State to demonstrate with a full scale pilot program the effectiveness of degasification technology.

That program successfully showed that degasification of water injected into the subsurface for storage/recovery can effectively control the release of arsenic from the soil formations. ASR-1 utilizes degasification membranes to remove 99.9% of the dissolved oxygen from the injected water and maintains arsenic levels in recovered water at background levels. With ASR-2, the City is utilizing a more cost-effective degasification technology, namely a gas stripping tower. The tower system is significantly less complicated to operate and maintain, and has operational cost that are 75% less than the degas membranes at ASR-1. ASR-2 is in the midst of cycle testing, which has thus far produced very encouraging results related to arsenic mobilization control.